A medical treatment, such as diagnosis, therapy, anesthesia, or the like, may be performed in a method of inserting a tube-shaped catheter near nerve fibers of various nerve systems in the human body to inject various kinds of drugs.
To perform such a medical treatment using a catheter set for nerve treatment, it is important to find out an accurate location of a nerve to be treated and effectively deliver a drug to the found nerve.
FIGS. 1 and 2 show a conventional catheter set for nerve treatment, which is used for the purpose described above.
The conventional catheter set for nerve treatment includes an internal needle 1, a cannula 2, and a catheter 3.
The internal needle 1 is a conductive metal needle. The cannula 2 and the catheter 3 are flexible synthetic resin tubes, and the internal needle 1 is accommodated inside the cannula 2. When the internal needle 1 is completely inserted into the cannula 2, only a portion of the end of the internal needle 1 is exposed to the outside of the cannula 2. In a state where the internal needle 1 is connected to an electric stimulator (not shown), the internal needle 1 is assembled with the cannula 2 as shown in FIG. 1 and is inserted inside the body tissue as shown in FIG. 3.
The outermost part of nerve fibers of a nerve system in the human body is surrounded by a cylindrical membrane called as a neurovascular sheath 5 as shown in FIGS. 3 and 4, and various kinds of nerve bundles 6 and blood vessels 7 pass along inside the neurovascular sheath 5.
In a state where the internal needle 1 is connected to a nerve stimulation needle of the electric stimulator, the end of the internal needle 1, which is exposed outside the cannula 2, and the end of the cannula 2 are inserted into the neurovascular sheath 5 to approach near nerve fibers, and a nerve stimulation symptom is induced through an electric stimulus to detect a location of a nerve fiber to be treated. Since the internal needle 1 is made of a conductive metal, the internal needle 1 delivers the electric stimulus from the electric stimulator to nerves, and by observing a reaction of a patient in response to the electric stimulus, it is determined whether the internal needle 1 and the cannula 2 have arrived at a target nerve.
After placing the ends of the internal needle 1 and the cannula 2 at a nerve 6 to be treated in the method described above, the internal needle 1 is extracted in a state where the cannula 2 stays there, and the tubular catheter 3 is inserted near the nerve fiber through a tube line of the cannula 2 as shown in FIGS. 2 and 4.
After the catheter 3 is completely inserted inside the cannula 2, the cannula 2 is extracted in a state where the catheter 3 stays there, and a drug is injected through an inner tube of the catheter 3 to continuously operate neural blockade or neuromodulation.
For example, a drug for alleviating a pain may be injected through the catheter 3 to alleviate a pain of a patient, an anesthetic may be injected through the catheter 3 to anesthetize a target nerve, and a drug may be injected to an adherent nerve part with a pressure through the catheter 3 to solve the adhesion of a target nerve.
However, since the catheter 3 is made of a very flexible material, in a process of a medical treatment using the conventional catheter set for nerve treatment as described above, the end of the catheter 3 may be located at a deviated place from a target nerve firstly found using the internal needle 1, thereby decreasing a treatment effect.
That is, even though the end of the catheter 3 is firstly located near the target nerve, in a process of extracting the internal needle 1 from the cannula 2, inserting the catheter 3 inside the cannula 2, and extracting the cannula 2 from the body tissue in a state where the catheter 3 stays there, such a problem that the end of the catheter 3 moves to a place apart from the target nerve occurs frequently. In this case, since a drug injected through the catheter 3 does not affect the target nerve, a treatment effect may be deteriorated, or a medical treatment may fail.
In addition, as shown in FIG. 3, when the end of the internal needle 1 is inserted inside the neurovascular sheath 5 while the end of the cannula 2 cannot be inserted inside the neurovascular sheath 5 by being caught by the outer wall of the neurovascular sheath 5, it is determined in the outside that the cannula 2 has arrived at the target nerve 6. However, as shown in FIG. 4, when the internal needle 1 is extracted, and the catheter 3 is inserted inside the cannula 2, since the catheter 3 is made of a flexible material and has a blunt end, the catheter 3 may not be inserted inside the neurovascular sheath 5 so that a drug cannot be delivered to the nerve 6, thereby frequently causing a treatment failure.
Meanwhile, the cannula 2 is made of a very flexible and smooth material to prevent a nerve damage. Therefore, if the internal needle 1 is inserted inside the cannula 2 several times to increase accuracy of a medical treatment, the end of the cannula 2 may be frequently damaged and torn by the internal needle 1. When the end of the cannula 2 is torn by the internal needle 1, it is more difficult than before to insert the cannula 2 inside the neurovascular sheath 5, thereby increasing the possibility of a treatment failure.
In addition, when a nerve treatment is performed using the catheter set for nerve treatment as described above, since the internal needle 1 is extracted to insert the catheter 3, it cannot be checked during injection of a drug whether the end of the catheter 3 is located near the target nerve, even when the catheter 3 is gradually inserted inside the tissue with a force to correct a location of the catheter 3, it cannot be checked whether the location of the catheter 3 approaches the target nerve. In this case, although a location of the catheter 3 may be detected in a method of checking an image projected by injecting contrast media through the catheter 3 and scanning radiation, this method has problems in that a patient is exposed to the radiation, it is difficult to determine an effect, it takes too much time and cost, and it is troublesome to perform the method.